AXI Bridge for PCI Express v2.4
43
PG055 June 4, 2014
Chapter 3:
Designing with the Core
The
refclk
input must be provided at the frequency selected by the value of
c_ref_clk_freq
. This clock is used to generate the two output clocks and is also the
clock used to drive the AXI4 bus.
The AXI4-Lite interconnect clock
axi_ctl_aclk
is driven by
axi_ctl_aclk_out
. The
axi_ctl_aclk_out
clock is rising edge aligned and an integer division of the
axi_aclk_out
clock.
The output clock frequency is 62.5 Mhz for x1 gen1 64-bit AXI interface, and 125 Mhz for
the remaining configurations.
Resets
The AXI Bridge for PCI Express core is designed to be used with the Processing System Reset
module for generation of the
axi_areset
input. When using the Vivado IP integrator to
build a system, it is best to connect the
perstn
pin of the host connector for PCIe to the
Aux_Reset_In
port of the Processing System Reset module. The bridge does not use
perstn
directly. Also, the
mmcm_lock
output must be connected to the
dcm_locked
input of the Processing System Reset module to make sure that
axi_aresetn
is held
active for 16 clocks after
mmcm_lock
becomes active. See
Note:
Be sure to set the correct polarity on the
aux_reset_in
signal of the proc_sys_reset ip
block. when
PERSTN
is active-Low, set the parameter as follows:
PARAMETER C_AUX_RESET_HIGH = 0
X-Ref Target - Figure 3-2
Figure 3-2:
System Reset Connection
!8)
0#)E
)0
MMCM?LOCK
0%234N
PROC?SYS?RESET
)0
$#-?,/#+%$
!UX?2ESET?)N
)NTERCONNECT?ARESETN
!8)!2%3%4N
AXI?ARESETN
8